Signal transmission system



y 1934- s. N. BARUCH 1,957,419

SIGNAL TRANSMISSION SYSTEM Filed-Aug. 13, 1931 I 2 Sheets-Sheet 2 gwuemtoz UNITED STATES PATENT OFFICE SIGNAL TRANSMISSION SYSTEM Sydney N. Baruch, New York, N. Y., assignor to H. Curab Inc., a corporation of New York Application August 13, 1931, Serial No. 556,921 8 Claims. (Cl. 250-47) This invention relates to an improved transcomprising an electronic tube such as a thermission system for signalling whereby a most mionic triode embodying the grid 11, hot electrode economical utilization of the available frequency or filament 12, and cold electrode or plate 13, spectrum is effected. with suitable A-battery 14 and B-battery 15 con- An object of my invention is to provide an imnected thereto in the usual manner. The plate 60 proved transmission system designed to transmit circuit includes an inductance 16, which may be a radio wave of constant frequency composed of variable, as is well known in the art. Condenser two component portions which are relatively dis- 17 is connected across coil 16. A piezo-electric placed with respect to each other in regard to crystal 19 is connected in the input circuit of the r phase of a varying degree, said displacement beoscillating audion. Resistance 18 and an induct- 65 40 In the drawings:

ing controlled in accordance with the signals imance 18 are connected in shunt to the crystal beposed upon the system. In its broad aspects my tween the grid and filament of the audion. The invention contemplates the radiation of a wave frequency of the oscillating circuit is controlled of constant frequency from one antenna. A secby the crystal 19 in the input circuit although 0nd wave of the same frequency is maintained in the position of that element may be varied as de- 70 synchronism with the first wave. This second sired. The energy of constant frequency from wave is modified in phase by means of a circuit this circuit is radiated from antenna 16. controlling element, which may be of the nature The other circuit 20 comprises similarly a of a critically variable condenser as disclosed in thermionic triode embodying the grid 21, hot

20 my copending application, Serial No. 333,901, electrode 22, and cold electrode 23, with suitable 75 filed January 21, 1929. This element serves the A- and B-batteries 24 and 25, respectively, and purpose of displacing the second wave in phase an inductance 26 in the plate circuit which may with respect to the first, within the limit of a also be adjustable in a manner well known in the single cycle, in accordance with the signals imart. A condenser 2'7 is connected across the plate pressed upon the variable capacity. These circuit. The input circuit of the triode comprises 80 signals may assume the form of sound waves or a resistance 28 in series with a coupling induc may be adapted for purposes of telegraphy. This tance 29, with a condenser 30 in shunt to this modified wave is radiated from a second antenna. circuit. Coupling inductance 29 is furthermore This practice results in the radiation of two comassociated with an inductance 31 in the plate cir- 0 ponent waves of constant frequency with the cult of the oscillating circuit 10 which acts as 35 phase position of one variably shifted with rea priming or entraining means for the oscillaspect to the other. When these waves combine tions generated in circuit 20 to force the same in a receiving antenna, the original signals are into synchronism with the oscillations in circuit reproduced by the proper rectification of the 10. However the input circuit is varied by means 35 combined radio frequency'wave. of a variable capacity microphone which is con- Other objects and purposes will appear from nected by means of conductors 43 and 4'7 across the more detailed description in the following condenser 30. This variable capacity is slight specification, in conjunction with the accomenough to vary the constants of the input circuit panying drawings. without changing its frequency, which effects a phase displacement of the oscillations in this Fig. 1 illustrates an embodiment of the transcircuit with respect to those normally generated mitting station embraced by my invention. therein. The specific construction of the micro- Fig.2 schematically illustrates a receiving staphone is disclosed in detail in my application, tion in cooperation with my transmitting station. Serial No. 333,901, filed January 21, 1929. The

45 Fig. 3 illustrates another form of my invention. variable control upon the oscillating circuit 20 Fig. 4 illustrates the form of my invention used is evidenced in the output coil 26, and is radiated in conjunction with a push-pull output circuit. from the antenna circuit 26'.

Fig. 5 illustrates my invention wherein the It is not essential for the operation of my sysenergy output is efiected through amplifiers upon term that the controlled oscillating circuit should 9 which is disposed. a unique differential capacity generate its own oscillations primed by the concontrol. trolling circuit. The controlled circuit which is Fig. 6 is a modification of the circuit portion modified in phase may be an amplifier of the K-L-M-N embodied in Fig. 5 and which may original energy. Thus in Fig. 3, is illustrated an be substituted therefor. oscillating circuit 10, generated by a piezo-elec- 5 In Fig. 1 is illustrated an oscillating circuit 10, tric crystal controlled audion in the manner described in explanation of Fig. 1. In addition to the elements illustrated in Fig. 1, a condenser 39 is associated with the crystal 19. A bias is also imposed upon grid 11 by a battery 49 through a suitable choke 50. The output of oscillating circuit l0, tuned by means of variable inductance 51 and capacity 52 is fed through a series of amplifiers C and D to the radiating circuit R. These amplifying circuits may assume various forms in accordance with the practices well known in the art. As illustrated, these amplifiers are of the three element type with electrodes 57, 58, 59 and 77, 78, 79 corresponding to grid, filament, and plate elements. A bias upon the grid element of amplifier C is provided by battery through inductance 54. Coupling condenser 53 segregates this potential from the circuit 10, at the same time coupling the energy from this circuit to the input of amplifier C. The output circuit of amplifier C, represented by inductance 72 and tuning condenser 71 is coupled to the input of amplifier D by means of coupling condenser '76. The output circuit of amplifier D consisting of variable capacity 80 and inductance 81 is coupled to the reactive elements 83 and 84 of the radiating circuit 83. The amplifying properties of the tubes C and D are controlled by feed-back condensers '70 and 85 associated with portions of inductances 71 and 81, respectively. An amplifier E operates relatedly to amplifier D, having the output of amplifier C impressed across the input circuit of the both of them. A biasing potential for both amplifiers D and E is obtained from battery '75 acting through choke coil '74. The elements of the amplifier E, correspond to those of amplifier D and the output therefrom is radiated from another radiating antenna R. However the microphone condenser 40 is connected across the tuning condenser 80', which serves to vary the. phase position of the radio-frequency wave in the output of circuit of amplifier E with respect to that of amplifier D. The resulting radio frequency waves radiated independently are thus radiated g with a varying phase displacement controlled in accordance with the signals imposed upon the microphone condenser 40.

My system is also adapted for application in the case that normally twowvaves are radiated which are displaced by 180 degrees. Fig. 4 illustrates a type of push-pull amplifier to effect such a transmission. The portion of circuit 3 to the left of line AA in Fig. 3, may be used with the amplifying system as illustrated in Fig. i. The output of amplifier C is capacitively coupled with the push-pull amplifier F-G through condensers 8'7 and 87. A grid biasing potential for the grids and 90' is obtained by battery 88 acting through chokes 89 and 89. The filaments 98 and 98 are energized by battery 97. Source of potential 96 constitutes the common plate supply for the plates 91 and 91. Of course the specific mode of energization for the various circuits may be modified as desired, the hereindescribed showing being the simplest. The output circuits of amplifiers F and G, and 100', may be tuned by variable condensers 94 and 94' in conjunction with inductance elements 93 and 93, respectively. Feedback condensers 92 and 92 cooperating with inductance portions 95 and 95' control the amplification properties of the two circuits. The output energies of the two circuits 'F and G are in turn transferred to antenna R denser 9a in circuit G. Thereby the normal relationship existing between circuits F and G is disturbed. The phase of the radio-frequency wave radiated from R varies from its normally opposed position to that radiated from R within the limit of a single cycle in accordance with the signals impressed upon the microphone condenser 40.

A unique form of control of my modulated energy is illustrated in Fig. 5. The portion of the circuit on the left of line A--A in Fig. 3 may be used with the amplification stages illustrated in this figure. Amplifier H, of the same general type as explained in detail in conjunction with Figs. 3 and i, is coupled to the output of circuit C through coupling condenser 104. The amplifier circuit I is connected at its grid to the output of circuit C through condenser plate 108 of microphone condenser 40 intermediate plates 107 and 109 connected across the output circuit of amplifier C. In the normal state of this circuit, only circuit H is receiving energy from circuit C and transferring the same to the radiating antenna R. Circuit I, connected with intermediate plate 108, receives no energy since the potentials impressed upon the latter are equal and of opposite phase. However a movement of plate 108 in either direction will cause a preponderant effect thereupon of either of the two external plates. This effect may be so critically designed that a transfer of energy of varying phase displacement may be accomplished to amplifier I and from there to the radiating antenna R.

A modification of the condenser microphone control described in conjunction with Fig. 5 is illustrated in Fig. 6. This circuit may be substituted for the portion enclosed in the block K--LM-N with the corresponding conductors X, Y, and Z in Fig. 5, connected to X, Y and Z in Fig. 6. A talking circuit 114 is illustrated comprising a microphone 115 and source of potential 116. Electromagnets 117 of equal strength but of opposite polarity control the movable condenser plates 112 and 113 cooperating respectively with fixed plates 111 and in a polarized manner. Thus at the instant when plate 112 would be drawn away from plate 111, plate 113 would be attracted toward plate 110. in the normal position of the condensers, conductor Z would have no potentials impressed upon it, as explained in conjunction with Fig. 5. However voice currents upon microphone 115 act to disturb the normal condition of the conductor feeding the input circuit of amplifier I to cause a radio wave to be radiated from its associated antenna R, which is displaced in phase from that radiated from antenna R, in Fig. 5.

As a result of the operations hereinbefore described, two sources of energy of the same frequency but relatively displaced in phase, are transmitted from the independent antenna. A receiving antenna 60 is designed to pick up these energies, and by means of coupling elements 61 and 62, the variable amount of energy imposed upon the receiving antenna is suitably detected in receiver 63, and the original sounds are reproduced in receivers 64 or an equivalent loudspeaker. The audio-frequency wave reproduced by the receiver 63 will depend upon the combination of the energies, and particularly with respect to the relative phase positions of these energies. The mode of operation may be so adjusted that a faithful reproduction of the sounds imposed at the transmitting end may be had at the receiving end.

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My system is as well adapted for telegraphy as telephony. Condenser 40 may be replaced by an ordinary key-switching condenser which is so designed as to shift the phase of the Wave generated in circuit 20 from that generated in circuit 10 within the limits of a single cycle. A suitable chopper is employed at the receiving station. The signals of the detected energies of different amplitudes, depending upon whether the switching key is effecting a phase displacement of one of the radiated sources of energy, correspond to the manipulation of the key at the transmitting station.

While I have described my invention in certain preferred embodiments, I desire it to be understood that modifications may be made and that no limitations upon the invention are intended other than are imposed by the scope of the appended claims.

What I claim is:

l. The method of signal transmission comprising the generating of a high frequency wave, controlling a second high frequency wave of the same frequency as the first wave by said first wave, radiating said first high frequency wave, modifying the phase position of said second wave relatively to said first wave within a single cycle in accordance with signals, and radiating said modified high frequency wave.

2. The method of signal transmission comprising the generating of a high frequency wave, controlling a second high frequency wave of the same frequency as the first wave by said first wave, radiating said first high frequency wave, modifying the phase position of said second wave relatively to said first wave within a single cycle in accordance with signals, radiating said modified high frequency wave, and receiving said high frequency waves in a receiver tuned to their common frequency.

3. The method of signal transmission comprising the generating of a high frequency wave, controlling the generation of a second high frequency wave of the same wave by said first wave, radiating said first high frequency wave, modifying the phase position of said second wave relatively to said first wave within a single cycle in accordance with signals and radiating said modified high frequency wave.

4. The method of signal transmission comprising the generating of a high frequency wave, amplifying said wave at two independent points, radiating said wave at one of said points, modifying the phase position of the wave at the second of said points relative to the wave radiated from said first point within a single cycle in accordance with signals, and radiating said modified high frequency.

5. In a signal transmission system, an oscillating circuit of constant frequency, an output circuit therein, radiating means for the energy de veloped in said output circuit, a second oscillating circuit associated with said output circuit whereby said second oscillating circuit is maintained in synchronism at said frequency with said first oscillating circuit, an output circuit in frequency as the first said second oscillating circuit, independent radiating means for the energy developed in said second circuit, and circuit controlling means in said second circuit for modifying the phase position of the output of said second oscillating circuit with respect to the output of said first oscillating circuit.

6. In a signal transmission system, an oscillating circuit of constant frequency, an output circuit therein, radiating means for the energy developed in said output circuit, a second oscillating circuit associated with said output circuit whereby said second oscillating circuit is maintained in synchronism at said frequency with said first oscillating circuit, an output circuit in said second oscillating circuit, independent radiating means for the energy developed in said second circuit, circuit controlling means in said second circuit for modifying the phase position of the output of said second oscillating circuit with respect to the output of said first oscillating circuit, and means for receiving the energies of said two output circuits tuned to their common frequency.

'7. In a signal transmission system, an oscillating circuit of constant frequency, comprising a thermionic tube circuit, a piezo-electric crystal in said input circuit, an output circuit, radiating means for the energy developed in said output circuit, a second oscillating circuit comprising a thermionic tube and an input circuit, means for coupling said output circuit with said last mentioned input circuit whereby said second oscillating circuit is maintained at said frequency of said first oscillating circuit, an output circuit in said second oscillating circuit, independent radiating means for the energy developed in said last mentioned output circuit, and circuit-controlling means in said second oscillating circuit for modifying the phase position of the output of said second oscillating circuit with respect to the output of said first oscillating circuit.

8. In a signal transmission system, an oscillating circuit of constant frequency, an output circuit therein, an amplifier connected to said output circuit, radiating means for the energy developed in said amplifier, a second amplifier connected to said output circuit, said latter connections comprising differentially controlled capacitance normally set to effect no energy transber between said output circuit and said second amplifier and adapted to transfer a wave displaced in phase within the limits of a single cycle from that transferred to said first amplifier in response to signals, said capacitance comprising a microphone circuit, two polarized electromagnets in said circuit, two condensers each having a fixed and movable plate associated with said electromagnets, the fixed plates of said condensers being connected across the output circuit, and the movable plates, adapted to be differentially controlled by the electromagnets, connected to the input circuit of the second amplifier, and means for independently radiating the energy of said second amplifying circuit.

SYDNEY N. BARUCH. 

